state-transition-test-design

Overview

Per ISTQB CTFL Syllabus v4.0.1 §4.2.4, "a state diagram models the behavior of a system by showing its possible states and valid state transitions. A transition is initiated by an event, which may be additionally qualified by a guard condition." This skill walks the derivation end to end: stateful spec in, human-readable manual test cases out (event sequences with per-step expected states, not code).

CTFL claims below come from the official v4.0.1 PDF (2024-09-15) fetched from istqb.org on 2026-06-10; the N-switch material comes from the CTAL-TA v4.0 syllabus §3.2.2 (fetched 2026-06-10). One worked example (account lockout) is carried through every step.

When to use